The general aims of the proposed research are to further elucidate the basic interrelationships which exist among the CNS, the pituitary gland release of LH and FSH, the ovary and the sex steriod positive and negative feedback mechanisms which modulate these events. To this end the specific aims of the proposal are: (1) to elucidate further whether LH regulates its own secretions and if so by what mechanisms. Do specific brain regions concentrate LH during the time of the preovulatory LH surge; do specific peptidase inhibitors affect the temporal patterns of LH release on proestrous in rats? What changes in medical basal hypothalamic and pituitary portal plasma LHRH occur following LH infusions and preoptic stimulation? What effects do LH infusions have in PGE2-induced LH release. Does LH infusion activate inhibitory systems within the hippocampus to reciprocally inhibit endogenous LH release. What are the turnover rates of catecholamines after MPOA stimulation and are they affected by LH? (2) we plan to determine further the CNS sites and mechanisms involved in the selective release of FSH using a variety of experimental protochols. What other CNS regions which when stimulated provoke the release only of FSH? Does Dorsal Anterior Hypothalamic Area (DAHA) stimulation inhibit the release of LH via effects within the median eminence and/or pituitary gland? Using "stop-gap" entry infusions of LHRH can the selective release of FSH be provoked? What ovarian secretion products are removed after ovariectomy or LH injection to permit FSH to rise in plasma. What are the effects of porcine follicular fluid on FSH rises and on oocyte maturation? (3) we wish to ascertain the regulatory role of estrogen and progesterone in facilitating (or inhibiting) the pituitary discharge of LH and/or FSH prior to and after the preovulatory surge.